Simplify Blender GUI, FileWindow without info header
No, there is no way to customize the window layout used when launching the file selector, unless you modify the C source code.

However Im not sure why this, specifically is such an important feature.

You could however, use Python's tkinter to launch a non-blender file-selector.

See:


https://docs.python.org/3.4/library/tkinter.html#module-tkinter
https://stackoverflow.com/a/15685836/432509